RUI: Probing the Structure of Excited Baryons that Decay through the Omega-Meson Channel

强力产生核引力，将质子和中子（也称为核子）束缚在原子核内。准确理解强核力是如何在原子核内部产生的，是当今核物理学面临的最大智力挑战之一。我们确实知道，强力是由称为胶子的粒子交换介导的，正是这种胶子相互作用占了核子质量的大部分。核子本身是由另外三种被称为夸克的粒子嵌入胶子的泡沫海洋中形成的。然而，我们对质子和中子是如何由夸克和胶子组成的知识，充其量也只是初步的。一个高能粒子，如电子或π介子，入射到核子上，可以直接与里面的一个夸克相互作用，激发夸克到更高的能量，使核子更重。这些激发态存在的时间最短，大约是万亿分之一秒的万亿分之一，然后衰变成其他粒子。产生的粒子类型以及它们在空间中的分布方式提供了关于核子组成的关键信息。该奖项颁发给拉马尔大学（一所主要是本科院校），支持指导本科生担任研究人员以及他们为进入研究生院和/或行业做准备。两个或三个本科生将在现场工作在托马斯杰斐逊国家加速器设施每年夏天十周，以协助在实验室正在进行的实验中的两个硬件和软件项目。为这项工作提供的培训包括学习如何设置计算机系统，编写高效的软件，运行检测器模拟，以及在拉马尔大学的高性能计算机集群等计算机集群上调度大规模计算。通过他们的实践经验，本科生将学习探测器实际工作的细微差别和复杂性。拥有良好的硬件技能将深刻洞察数据分析最终结果的可靠性，这些技能受到研究生院以及处理大数据和数据分析的行业的高度追捧。学生们还将学习时间管理的软技能和团队合作的整体重要性。该奖项支持杰斐逊实验室（美国）、艾尔莎（德国）和J-PARC（日本）通过使用线性偏振光子束、偏振电子和π+/π-介子（π+/π-）来研究核子的基本性质和结构。强核相互作用是导致从夸克与胶子的结合、夸克与无色强子的结合、核子与核的结合以及大核的集体行为等大距离尺度现象的原因。PI和他的团队将寻求问题的答案，例如当海夸克和胶子贡献最小时，价夸克如何自组装，胶子如何附着在夸克上以增加当前夸克的质量到组成夸克的质量，以及夸克如何在核子内共振以形成激发的夸克组装。 该小组的目标是了解夸克和胶子集合的涌现行为和结构。 在JLab和艾尔莎的实验中，这些研究的探针将是Ω介子。通过清晰明确的ω介子信号来探测N* 共振态的结构具有很大的发现潜力。此外，有一个显着缺乏的数据，重子共振衰减通过欧米茄模式作为Q2的电磁通道，这是需要了解强子质量的出现。 PI将使用耦合通道方法的π介子束数据，以确定和协助振幅分析的2 π介子衰变通道，这是进一步了解强子mass.This奖的出现反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

The strong force gives rise to the nuclear attractions that bind protons and neutrons, otherwise known as nucleons, together inside the nucleus. Understanding exactly how the strong nuclear force is generated inside the nucleus is one of the greatest intellectual challenges facing nuclear physics today. We do know that the strong force is mediated by the exchange of particles known as gluons, and it is this gluon interaction that accounts for most of the mass of the nucleon. The nucleons themselves are formed of three other particles called quarks embedded in a frothing sea of gluons. Our knowledge of how protons and neutrons are constructed from their quark and gluon constituents, however, is rudimentary at best. An energetic particle, such as an electron or a pi-meson, incident on a nucleon can interact directly with one of the quarks inside, exciting the quark to higher energy, making the nucleon more massive. These excited states exist for the briefest of moments, on the order of a trillionth of a trillionth of a second, and then decay into other particles. The types of particles produced and how they are distributed in space provide key information on the make-up of the nucleon. This award to Lamar University, a Primarily Undergraduate Institution, supports the mentoring of undergraduate students as researchers and their preparation for graduate school and/or industry. Two or three undergraduate students will work onsite at the Thomas Jefferson National Accelerator Facility for ten weeks each summer to assist in hardware and software projects at two of the ongoing experiments at the Laboratory. The training provided for this work includes learning how to set up computer systems, writing efficient software, running detector simulations, and scheduling large-scale computations on a computer cluster like the High Performance Computer Cluster at Lamar University. Through their hands-on experience, the undergraduate students will learn the nuances and intricacies of how detectors actually work. Having good hardware skills will give profound insight into the reliability of the final results from data analysis, skills that are highly sought after by graduate schools as well as by industries that deal with big data and data analytics. The students will also learn the soft skills of time management and the overall importance of working together in a team.This award supports the study of the fundamental properties and structure of nucleons through using a beam of linearly-polarized photons, polarized electrons and pions (π+/π–) at Jefferson Lab (USA), ELSA (Germany), and J-PARC (Japan). The strong nuclear interaction is responsible for phenomena over a large distance scale from the binding of quarks by gluons, the combinations of quarks into colorless hadrons, the binding of nucleons into nuclei, and the collective behavior of large nuclei. The PI and his group will seek answers to questions such as how valence quarks self-assemble when sea quark and gluon contributions are minimal, the nature of how gluons attach to quarks to increase the mass of current quarks to that of constituent quarks, and how quarks resonate inside the nucleon to form excited assemblies of quarks. The group aims to understand the emergent behavior and structure from assemblies of quarks and gluons. In the case at JLab and ELSA, the probe for these studies will be the omega meson. There is great discovery potential in probing the structure of N* resonances through the clean and unambiguous signal of the omega meson. Moreover, there is a significant dearth of data of baryon resonances decaying through the omega mode as a function of Q2 for the electromagnetic channels, which is needed to understand the emergence of hadron mass. The PI will use a coupled-channel approach to the pion-beam data to ascertain and assist in amplitude analysis for the two-pion decay channel, which is further necessary for understanding the emergence of hadron mass.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.